Cannon ball ?

[tomytye]

I used to make balls for my flintlock and cap muzzle loaders. And always hav a nub to cut off. I believe I found a colonial/pre colonial cannon ball with a nub. There was a nefarious character hanging out where I’m detecting as well as drilling grounds for milita men that purportedly made themselves known in Lexington mass. Anyways I wire brushed around the “nub” and it appears to be the same material with no cracks found. I know zip about cannonballs. It it 3.17” or 80mm in diameter and a touch over 5 lbs. Is it a cannonball? And is it an explosive or conventional cannonball? Any help appreciated.